Supervisory control system



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July 4, 1939. H. P. BOSWAU 2,164,379

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TAU/K510i)! INV-ENTOR Hans P. Bosazau.

ATTOR EY WITNESSES Patented July 4, 1939 a 1T STATES PATENT .QFFI'CE' I SUPERVISORY CONTROL SYSTEM Hans P. Boswau, Gallon, Ohio Application June 7, 1934, Serial No. 729,456

19 Claims. (01. 177-353) My invention relates generally to electrical control systems and it has particular relation to supervisory control systems. I t

It has been. the practice in the past to pro.-

5 vide supervisory control systemswhich are arranged to operate over a single pair of conductors and which are so designed as to provide for theoperation of a relatively large number of points of control. In the systems of the prior art-which have been developed on this basis, it has been necessary to provide a large number of relays serving as the common equipment in view of the large number of points which it may be desirable to control. Such a systemis shown in Patent No. 1,714,966 to Wensley et a1. Ordinarily,

the common equipment is not dependent upon the number of points which are controlled since the same common equipment is required Whether five or fifty points are to be controlled. These systems are not only complicated but also they are expensive in the first cost, and further are expensive to maintain. It is,.therefore,desirable to reduce the number of relays-or other apparatus to a minimum in order to,-.reduce the first cost and to decrease the operating expense to a minimum. h

In many instances; it is desired to control only a. relatively small number of points at a substation from a main station or ofiice. Therefore,

I have provided a supervisory control system which may be employed for controlling the operation of a limited number of points, such as five, and I have. specifically designed the apparatus and circuitswith a view to reducing the amount of equlpmen'trequired toa minimum.

In view of the fact that itisnotintended to control a large number of pointsthe common equipment may be reduced to a minimum with the corresponding reduction in first cost and expense of operation. l F

The object'of my invention, generally stated, is to provide a supervisory'control system which shall besimple andefficient in operation, and which may be readily and economically manuiactured and installed.

Theprincipail' object of my invention is to provide for controlling a pluralityof conditions from a remote point. v

- Animportant object of my invention is to provide for transmitting one of a plurality ofzimpulses'of' different polarity and lengthto a remote station over a single signalling circuit in order to select at the remote station a point individual to the impulse.

Another important object of my invention is the appended claims.

to provide for transmitting from a main station or oflice one of a plurality of selection impulses of different polarityand length to a remote station or sub-station over a'slngle signalling circuit, in order to select at the remote. station 5 an operating point individual to the impulse, andfor transmitting from the remote station to the main station a check impulse individual to the point selected to check theselection.

Still another important object of my inven- 10 tion is to provide for applying to the signalling circuit a timed operation impulse in order to efiect a predetermined operation-individual to. the-impulse at the selected point.

.Another ,object of my invention is to provide 16 for comparing a voltage at the remote station witha voltage. indicating the state of a variable condition at the. remote station in order to provide an accurate indication at the main station of the stateof the condition at the remote sta- 20 tion.

Still another object. of my invention is to provide for simultaneously effecting a change in a; condition .at the remote station and indicating the changeasit takes place at the main station.

A still further object of my invention is to provide for arresting further chan'gein the condition and automatically indicating at the main stationthe state of the variable condition at the terminationof the-change. Y

Othercobjectsof myinvention will, in part. be obvious and,-in part, appear hereinafter. Y

My invention accordingly is disclosed in the embodiment hereof 'shown in the accompanying drawinga and comprises. thefeatures of con- 36 struction cornbinationof elements, and arrange,-

ment of parts '-which-.-will beexemplifled ,in the construction hereinafter set forth and. the scope of the application of which will be indicated in For a more complete understanding of the nature and scope of my invention, reference may be had to the following detailed description,

,taken in connection with the accompanying drawings, in which; r v Figures 1, 2 and 3 illustratediagrammatically the circuit connections and apparatus which are provided at theoflice or main station;

Figs. 4, 5 and 6 illustratediagraminatically the circuit connections and apparatus which are provided at the remote-station or sub-station;

and, h

Fig. 8 illustrates graphically the codes which are employed for performing certain operations after a. point has been selected and checked.

Generai description In order to fully set forth the functioning of my new supervisory control system, it will be described in connection with the remote control of a hydro-electric power plant from a central or main station or oflice. It will be understood. however, that this description is merely illustrative and that the invention could be practiced for the control of various other types of equipment and for the obtaining of indications of variable conditions and initiating changes therein other than those illustrated and described herein.

According to this invention, I have provided for controlling five points at the sub-station and Q I have provided five corresponding control points at the ofllce. Points Nos. I and at the substation are associated with main line feeder cir cuit breakers. The circuit breakers are provided with closing and tripping mechanisms which may I be controlled from the corresponding control points at the oifice. In addition, it is also possible to supervise the condition of the circuit breakers individual to points I and 5 and, accordingly, supervisory signals are provided at the I corresponding control points at the oifice by means of the customary red and green indicating lights to indicate whether the circuit breaker is in the closed or tripped position.

In the event that a fault occurs at the substation, such as a short circuit on the generator or some other like occurrence which would cause the-station to be locked out, it is desirable to have an indication of the position of the main circuit breaker at the oflice. However, it is undesirable to provide for controlling the main circult breaker from the ofllce in view of the fact that it is not automatically tripped unless some serious fault occurs at the sub-station, which necessitates an investigation before the circuit breaker should be reclosed. Therefore, point No. 2 is provided at the sub-station, which is arranged to provide only an indication of the condition of the main circuit breaker at the corresponding control point No. 2 at the ofllce.

The load which the generator at the hydroelectric station can carry depends to a large extent upon the head of water which is available for operating the water turbine. It is, therefore, desirable to provide at the ofllce some means forgiving an indication of the water level in order that the operator can determine whether or not the particular hydro-station is properly loaded. For this purpose, No. ,3 point at the sub-station is provided, which is arranged to transmit to the corresponding No. 3 point at the oiilce, an indication of the water level.

The load on the generator may be varied by increasing or decreasing the amount of water which is permitted to flow through the water turbine. In turn, the flow of water is regulated by means of a gate. It is desirable to provide at the oflice not only means for opening and closing the gate, but it is also desirable to provide means for indicating to the operator the position of the gate. It is further desirable to provide the operator with a continuous indication of the movement of the gate simultaneously with its movement so that further movement may be arrested as soon as, in the judgment of the operator, the gate has been opened to the desired extent. Points No. 4 at the omce and sub-station are provided for eflecting these functions. By means of apparatus associated with these points, it is possible not only to, raise and lower or to open and close the gate, but it is also possible to obtain a continuous indication of the change in position of the gate simultaneously with the change taking place thereat.

Although the supervisory control system has been illustrated and described herein in connection with certain types of apparatus units individual to each of the points at the sub-station, it will be understood that other combinations of apparatus units may be used. Thus it may be desirable to provide all five of the points for controlling and supervising the operation of circuit breakers. In another instance it may be desirable to provide for supervising the operation of one or more circuit breakers. In still another instance, it may be desirable to obtain indications of the levels of liquids or the pressure of gas or the like and to open or close valves orto perform other functions. It will, therefore, be understood that the particular apparatus units associated with the points at the sub-station illustrated and described herein are used for illustrative purposes only.

In order to select any one of the five points atthe sub-station different impulses are employed, each of which is individual to a particular point. In addition, when it is desired to select a point at the offlce due to an operation at the substation, the same code impulse is transmitted. In order to check the selection an impulse individual to the point selected is transmitted to the station originating the selection impulse. In the embodiment of the invention described herein, only points I, 2 and 5 at the sub-station are arranged to originate selection impulses, while at the office each of the five points is arranged to select a. corresponding point at the sub-station.

By the term impulse" I mean the application of a positive or negative voltage to a circuit comprising two conductors. Thus, considering a circuit comprising conductors LI and L2, which are provided as illustrated herein for connecting the office with the sub-station, a positive impulse is applied to the circuit when the positive terminal of the battery at the office is connected to conductor LI and the negative terminal of the battery is connected to the conductor L2. Similarly, when the negativeterminal of the battery is connected to the conductor LI and the positive terminal of the battery is connected to the conductor L2, a negative impulse is applied to the line. It will, therefore, be understood that when in the specification and claims the term "positive impulse is mentioned, the term means that conductor Ll is connected to the positive terminal of the battery at the ofllce, or the substation, and that the conductor L2 is connected to the negative terminal of the battery at the oillce or at the sub-station. Likewise, when the term negative impulse" is used it will be understood that the conductor Ll is connected to the negative terminal of the battery at either the office or the sub-station. and that the conductor L2 is connected to the positive terminal of the battery at either the omce or the sub-station.

In order to select any one of the five points at the sub-station an impulse individual to that point is applied to the line connecting the stations. As illustrated in Fig. '7 of the drawings, a short positive impulse is applied for selecting point No. I while a short negative impulse i.

provided for selecting point No. I. In order to select point No.1 a positive impulse of longer duration than the short impulse is provided and this is termed a long positive impulse. Similarly, point No. is selected by applying to the line a negative impulse which is longer than the short negative impulse and this will be termed a long negative impulse. Point No. 3 is selected by app ying to the circuit a short positive impulse followed immediately by a short negative impulse. From theforegoing it will be observed that a timed impulse individual to each point may be transmitted from the office to the substation in order to select a point at the latter corresponding to the impulse which is individual thereto.

After a point at the sub-station has been selected it is desirable to have the point selected originate a check impulse, which will cause an indication to be given to the operator that the point which has been selected is the-point which he has desired to select. Therefore, as soon as any particular point has been selected, a,check impulse is transmitted to the station originating the selection impulse. As illustrated in Fig. 7, a check impulse is provided for each point which is individual to' that particular point. Thus, when point No. I

impulse respectively,

the selection to indicate to the operator that the correct selection has been made. Short positive and negative impulses are provided, respectively, for checking points Nos. 2 and 5. It will be observed that point 3 is checked by means of the short positive impulse followed immediately by the short negative irnpulse. The combination of selection and check impulses has been so chosenas to provide approximately the same length of time for each paint to complete the selection andcheck opera on.

After a point has been selected an operation impulse is transmitted to the selected point'in order, to effect an operation at that point which is individual to the operation impulse that is transmitted. While it will be understood that only points I, 2 and 5 may originate selection impulses, the following description will generally be based upon the selection impulses originating at the oiiice, although it will be understood that selection impulses may be originated at these points at the sub-station.

Referring particularly to Fig. 8, it will be ob served that the position of the circuit breaker at points I, 2 and 5 is checked by transmitting a short positive impulse. In like manner, this same impulse is applied to either points 3 or 4 for switching from the full scale to the actual meter reading for'a purpose which will be set forth hereinafter. Also, the short positive impulse may be applied to stop further operation of the gateoperating mechanism which is associated with point No. 4. After the circuit breaker at points I, 2 and 5 has been closed a short positive impulse will be applied to the line in order to indicate this fact to the operator.

When it is desired to trip either of the cirs cuit breakers associated with points I or 5, a long positive impulse is applied to the line or signalling circuit. This same impulse is also applied to the signalling circuit when point No. 4 has been selected and it is desired to close the gate.

In order to close the circuit breakers associor point No. I has been selected a long positive impulse or a long negative been selected, which points correspond to the circuit breaker, the position of which has changedfthereby originating the short negative impulse.

After the operator has completed any desired sequence of operations or in'the event that the system should become inoperative due to faulty functioning of certain of the relays, the entire system may be released to normal by the application of an extra long positive impulse to the signalling circuit.

Description of scheme of operation 'With a view to setting forth the fundamental scheme of operation of my invention, a short description thereof will be given. The following detailed description will then be more read-, ily understandable and it will not then be necessary to again set forth the reason for certain operations taking place.

Each of the stations is provided with a pair of oppositely connected polarized relays which are adapted to be connected to the signalling circuit connecting the stations. One or the other of the polarized relays is adapted to be pulled on the application of the impulse for which it is adapted to be pulled. Thus, on the application of a positive impulse to the signalling circuit, the positive line polarized relays will be pulled. In like manner on the application of a negative impulse to the signalling circuit, the negative line polarized relays are pulled.

Throughout the specification and claims the terms pulled? and dropped are employed in order to designate respectively that a relay has been energized or deenergized. It is thought that these terms are somewhat more descriptive of the functioning of the relays when they are energizedor deenergized, and therefore, these terms will be used with this meaning.

Each station is also provided with a positive and a negative sending relay. It will be understood that the positive sending relay is arranged to apply a positive impulse to the signalling circuit while the negative sending relay is arranged to apply a negative impulse to the signalling circuit. l

A positive receiving relay and a negative receiving relay are provided at each station, and are adapted to be pulled on the application to the signalling circuit of either a positive or a negative impulse.

.When a short positive or negative impulse isapplied to the signalling circuit, thecorresponding line relays at both stations will be pulled,

' thereby causing the pullingof either the posicompleted which cause the simultaneous selection of point selection relays at the omce and the substation. After the point selection relays have been pulled, no further selection can take place, due to the fact that a selection cut-oi! relay is pulled. The foregoing described selection will take place in connection with the selection of either points Nos. l and 4.

As set forth hereinbefore, in order to select points 2 and 5 long positive or negative impulses are applied to the signalling circuit. These impulses are applied by arranging to pull the positive and negative sending relays for a time much longer than that during which they are pulled for transmitting the short positive and negative impulses. relays are held pulled for the extra long time by the provision of a long impulse sending relay which is arranged to drop out only after the expiration of an extra long time. The pulling circuits for the positive and negative sending relays are controlled by the long impulse sending relay and, therefore, they are not dropped until a preto points 2 and 5 which effect the pulling of the corresponding point selection relays.

In order to select point 3 both the positive and the negative sending relays are simultaneously pulled. However, the positive sending relay is arranged to first pull the positive line relays at both stations. As soon as the positive line relays are pulled the circuit to the positive sending relay is opened and after the expiration of a predetermined interval, it drops. A circuit is then completed immediately for pulling the negative line relay, and after the expiration of a predetermined interval, the negative sending relay drops. Thus, a short positive impulse is transmitted followed immediately by a short negative impulse. In response to the pulling of the positive and negative line relays the positive and negative receiving relays are both pulled. During the interval when both of these relays are pulled, circuit connections are completed for pulling the point selection relays individual to points 3 at the oillce and sub-station.

At the end of the transmission of an impulse from either station, sending control relays are provided for preventing the transmission of another impulse from the same station, and in addition, the sending control relays complete circuits in preparation to the receipt of a successive impulse from the station not originating the first impulse.

After any one of the five points has been selected at the sub-station, for instance, the check impulse individual to the point selected is transmitted to the oflice in a manner similar to that in which the selection impulse was transmitted from the ofllce to the sub-station. Due to the fact that the point selection relay at the ofllce individual to the point which it is desired to control has been pulled, the operator is informed by means of the illumination of a stop lamp. that the correct point at the sub-station has been selected, if

such is the case.

After the proper selection and check of selection has been made, the operator may check the position of the apparatus unit at the sub-station by depressing a check key. If the operator has selected point No. I at the sub-station, a short positive impulse will be transmitted in order to check the position of the circuit breaker asso- The positive and negative sending" ciated with this point. n the circuit breaker is in the closed position, a short positive impulse will be returned to the ofllce. and if the red indicating light on point No. l is illuminated, no change will take place. However, if the green light is illuminated, it will be extinguished and the red light will be lighted. Had the circuit breaker associated with point No. I been in the open position, a short negative impulse would have been returned to the office indicating that the circuit breaker was tripped. If the red indicating light associated with point No. l at the ofllce had been illuminated, it would have been extinguished and the green light would have been lighted to indicate to the operator that the circuit breaker was in the tripped position.

After the position of the apparatus unit has been checked, the operator may desire to change its position. He then operates the twist key individual to the point under control to the desired position, and depresses a master control key. Referring again to point No. l and assuming that it has been selected, and the operator has found that the circuit breaker associated therewith is in the open position, and he wishes to close it, the operation of the master control key causes the sequence of short positive and negative impulses to be applied to the signalling circuit to effect the closure of the circuit breaker. Had the circuit breaker been-closed, and the operator desired to trip it, the depression of the master control key would efi'ect the application of along positive impulse to the signalling circuit to effect the desired operation.

When it is desired to obtain an indication of the position of the gate associated with point No. 4, the operator causes this point to be selected in the manner set forth hereinbefore. As soon as point No. 4 is selectedpthe gate position meter associated with point No. 4 at the office gives an indication which corresponds to the voltage of the battery at the sub-station. On operating the check keypa short positive impulse is applied to the signalling circuit, which causes a change in circuit, so that the gate position meter is connected across a potentiometer at the sub-station. The potentiometer isconnected across the substation battery and it is operated in accordance with the movement of the gate. Thus, at all times, the voltage across the potentiometer. or what may be termed as the potentiometer voltage, gives an indication of the position of the gate.

Since the position of the gate is a function not only of the potentiometer voltage, but is also a function of-the battery voltage which may vary, it will be understood why the battery voltage at the sub-station is first measured. The gate position meter is provided with two scales, one of which is calibrated in percent of battery voltage and the other in terms of gate position. Thus,

when the gate position meter is connected across the potentiometer voltage, the actual gate position may be obtained by dividing the position scale reading by the percent reading of the normal battery voltage.

The operator may now initiate a raising or lowering operation of the gate by actuating the twist key and master control key at point No. 4 to transmit either a "raise" me "lower impulse to the second station. The raise" impulse is a short positive impulse followed by a short negative impulse. The lower impulse is a long positive impulse. The transmission of this impulse effects the operation oi either the raise" or the "lower relay at the second station which in turn initiate the operation of the gate actuating mechanism (not shown). During this operation, the indicating meter and potentiometer have been disconnected from the signalling circuit but when the initiation of the raise or lower operation has been completed the meter and potentiometer are again reconnected and give a continuous indication of the change in gate position taking place.

11 The raising or lowering operation may be ter minated by operating the check key to transmit a short positive impulse which effects the release of either the "raise or lower relay as the case may be.

After a desired sequence of operations has been performed, and the operator desires to restore the set to the normal condition, the point operate key individual to the point which has been operated is released. As a result, circuits are completed for effecting the pulling of the positive sending relay for an extra long time. This operation releases all of the relays which had been pulled, due to the sequence of operations necessary to obtain the desired control and indication functions, and restores them to normal in a manner which will be set forth in detail hereinafter.

Description of apparatus In order to more readily locate the relays,

switches, twist keys, indicating lights and the like,

a reference character has been applied to each, the first numeral of which indicates the sheet on which the element possible, the next numeral indicates the point with which the particular element or piece of apparatus is associated. The contact members of the relays are identified from left to right and from top to bottom by small letters. In like manner, the contact members of the twist keys and point operate keys are identified from top to bottom. The letter indicating the contact members will be employed throughout the specification immediately after the reference. character applicable to the relay, twist key or the like. Thus, the reference character lBlc means the fourth set of contact members reading from left to right of the relay identified as IBI, which appears on sheet 1 and which is associated with point No. I.

Point equipment at the oflice The five control points atthe office are illustrated in Figs. 1 and 2 of the drawings. Each of the points is provided with a point selection relay which are identified as B relays. The point selection B relays are pulled in response to a selection of a point. in order to provide for subsequent operations on the point selected.

Points l, 2 and 5 are provided with point lamp relays which are termed C relays. The C relays are provided for controlling the energization of the red and green indicating lamps which are associated with each point. Points 3 and 4 are provided with a common meter switching relay I03 for transferring the indicating meters associated may be found. Insofar as only these points are employed to effect control functions at the sub-station. The twist keys for these points are identified as follows: ITKI, 2TK4, and I'I'KI.

In the event that the position of the twist keys associated with points I and 5 does not agree with the position of the apparatus, disagreement lights Ill and HI will be lighted.

The operator is informed as to whether or not a circuit breaker at the sub-station associated with a particular point is in the opened or the closed position by means of the customary red and green indicating lamps. Since points I, 2 and 5 are associated with circuit breakers, they alone are provided with the red and green indicating lamps. The red indicating lamps individual to each point are respectively as follows: H3, I23, 253.

When the operator desires to select a particular point for performing any of the operations individual thereto, heoperates a point operate key individual to each which will be set forth in detail hereinafter. The point operate keys individual to each point respectively are asfollows: IPOKI, IPOK2, |POK3,, 2POK4, 2POK5.

The green lamps individual to each point respectively are as follows: H4, I24 and 254.

As has been set forth hereinbefore, points 3 Point No. 4 is associated with the gate operatingmechanism and a gate position meter 245 is provided for indicating the position of the gate. It will be understood that the meters |35-and 245 are of the ordinary direct-current volt-meter type. They are arranged to measure the voltage across a potentiometer which is a function of the condition, the state of which it is desired to have an indication.

.After a point has been selected and checked and it is desired to perform an operation, the master control key ZMCK may be depressed. The master control key is of the non-holding type, so that as soon as the operator removes his finger from it, it is immediately restored to the normal position.

After a point has been selected and the 'selection has been checked, it may be desirable to check the position of the apparatus unit associated therewith in order to ascertain as to whether or not the indicating lamps individual thereto at 'the oilice correspond correctly with the position of the apparatus unit. For this purpose, a check key 20K is provided. check key is also of the non-holding type and it is immediately released as soon as operating pressure is removed therefrom.

In order to .restore the set to the normal condition after a series of operations has been completed, or if the set for some reasonrefuses to function, it may be re-set by means of a reset key 2RK. This key is type and it releases immediately upon the l emoval of operating pressure. a

In the event that one of the circuit breakers at the sub-station automatically trips, an alarm is given by means of an alarm light CAL which continues to be lighted until the reset key 2RK also of the non-holding is operated to restore the set to the normal operating position.

It is desirable to provide the operator with an indication of the particular circuit breaker which has automatically tripped in order that he may quickly be informed as to the condition of the apparatus at the sub-station. For this purpose, disagreement lamp flicker relays 232 and 233 are provided which are arranged to alternately ene gize and deenergize the disagreement lamp associated with the point which, in turn, is as: sociated with the circuit. breaker that has tripped. The disagreement lamp flicker relays 232 and 233 are of the extra slow-to-deenerglze or drop out type.

As soon as any one of the point operate keys is operated to select the point associated therewith a start relay 220 is pulled and remains pulled until the set is restored to normal. After a point has been selected an operation control relay 218 is pulled as soon as the master control key is operated, in order to insure the completion of the cycle of operations even if the master control key is immediately released.

A check control relay 2l9 is provided having two pulling windings which may be identified as M91. and 2l9R. The winding 2l9L is energized to pull the relay on the operation of the check key 20K. The winding 2BR is energized to pull the relay 2|9 and light the alarm lamp 2AL in the event that one of the circuit breakers at the sub-station should be automatically tripped' After a point selection has been made, a selection cut-off relay 2 is pulled in order to insure that no further selections will be made until the point which has been selected is released, and the set is restored to normal.

Point equipment at sub-station Referring now particularly to Figs. 5 and 6 of the drawings, it will be observed that the point equipment individual to each of the apparatus units at the sub-station is there shown. Point selection relays which may be termed F relays are provided, each of which is individual to a point. These relays are as follows: SFI, SE2, SE3, F4 and SEE.

A point supervision relay which may be termed a G relay is also associated with each point. These relays are as follows: 5Gl, 5G2, 5G3, G4 and 6G5. It will be observed that point supervision relays 5Gl, 5G2 and 6G5 are of the extra slow-to-deenergize or drop-out type.

Points I, 2 and 5 are provided with point start relays which are normally pulledand which when dropped due to an operation at the sub-station, initiate the selection from any one of these points of the corresponding point at the office. These relays are as follows: SHI, 5H2, and CH5.

As has been set forth hereinbefore, it is desirable to obtain an indication of the voltage of the battery at the sub-station before measuring the potentiometer voltage which corresponds to the condition, the state of which it is desired to obtain. It is, therefore, desirable to provide for switching the meters associated with points 3 and I from measuring the battery voltage to measure the potentiometer voltage. For this purpose, indicator switching relays 533 and 6H; are provided individual to points 3 and 4.

, It will be recalled that points i and 5 areassociated with circuit breakers and that it is intended that the circuit breaker associated with these points may be controlled from the oflice. For this purpose, trip relays 5Ti and 5T5 are provided. In order to close the circuit breakers, close relays SCI and 3C! are provided. It will be observed that contact members associated with the trip and close relays are provided, which may be connected to a control circuit for effecting the desired functioning of the circuit breaker. Since these circuits are old and well known, they will not be shown or described herein. Each of the circuit breakers associated with points I and i is provided with an auxiliary switch which may be identified as SASI and ASS, respectively. The auxiliary switches are provided for controlling the pulling and dropping of the point supervision relays as will be set forth in detail hereinafter.

Since point No. 2 is a supervision point only, no close and trip relays are provided therewith. The circuit breaker, however, associated with point No. 2 is provided with an auxiliary switch BASI, which is arranged 'to control the functioning of point supervision relay 5G2.

As has been set forth hereinbefore, a potentiometer is provided, the functioning of which is arranged to correspond to the water level. Since point No. 3 is provided in order to obtain the water level indication, a potentiometer 533 is provided, the position 'of the movable contact of which may be controlled by the level of the water in any well-known manner. As illustrated, the

potentiometer 530 is arranged 'to be connected across the sub-station battery. It will, therefore, be apparent that the voltage existing between the negative terminal of the potentiometer 530 and its movable contact is a function of the water level.

Point No. 4 is arranged to control and indicate the position of the gate, which in turn, controls the flow of water to the water turbine, which drives the generator at the sub-station. .The position of the gate is indicated by means of a potentiometer 640, which is connected as illustrated, across the sub-station battery. The movable contact of the potentiometer 6" is arranged to be moved in accordance with the movement of the gate. Thus, the voltage existing between the negative terminal of the potentiometer ill and its movable contact is a function of the gate position. In order to decrease the gate opening or to lower it, a lowering relay BL is provided. In like manner, in order to open or raise the gate a raise relay 3R4 is'provided.- It will be observed that contact members are provided on the lower and raise relays for connection to the necessary circuit arrangement for effecting the desired control of the gate position. In view of the fact that any well known circuit connections may be used for effecting the raising and lowering of the gate,

they will not be shown ordescribed in this specification.

Common equipment at the 011102 Referring particularly to Fig. 3 of the drawings,

it will be observed that apparatus which is common to all of the points at the oiiice is illustrated.

Positive and negative line relays 3M and 332 are provided and are arranged to be pulled on the application of either positive or negative impulses to the signalling circuit comprising the conductors LI and L2. Associated with each of the line relays 3M and 382 is a rectifier of the less expensive than what are commonly termed polarized relays" by the trade. However, their signalling circuit between the stations. Each of the receiving relays is provided'with a pulling winding, which is identified by the letter P, and a. holding winding which may be designated by the letter The two windings are provided in order to permit the receiving relays to remain pulled after the pulling circuit has been opened. Associated with both of the receiving relays is. a neutral receiving relay 305 which is of the slow-to-deenergize or drop-out type. The neutral receiving relay 305 controls the circuit to the holding windings of the receivingrelays 303 and 304, so that they will remain pulled until the neutral receiving relay 305 drops.

When a long impulse either positive or negative is received, along impulse receiving relay 306 iscaused 'to drop. This relay is of the extra slowto-deenergize or drop-out type, and will take-considerably longer to drop out after its winding has been deenergized than what is known as the slow-to-deenergize type of relay.

The positive and negative impulses are applied to the signalling circuit by means of positive and negative sending relays 301 and 308, respectively. These relays are of the slow-to-deenergize or drop-out type. The contact members of the sending relays are so arranged as to apply either a positive or a negative impulse to the signalling I circuit but are arrangedin such manner that the two impulses cannot be applied simultaneously.

In order to send a long positive or. negative impulse, a long impulse sending relay 309 is provided. It will be observed that relay 303 is of the extra slow-to-deenergize or drop-out type.

After an impulse has been transmitted from the office, a sending control relay 3| is pulled. This relay, in combination with a second sending control relay 3, is arranged to prevent the sending of a second impulse from the ofliceafter an impulse has once been sent and the combination of relays is arrangedto condition the circuits for receiving the'next impulse from the sub-station. It will be observed that the sending control relay 3 is provided with a pulling winding which may be designated by the letter P and a holding winding which may be designated by the letter H. The holding winding is provided for maintaining therelay 3|| pulled under certain conditions when the pulling winding isnot maintained energized.

After an impulse has been transmitted from the ofiice to thesub-station, the circuits are transferred so that the check impulse may be received. This is accomplished by means of a switching relay 3|3, which is of the slow-to-deenergize or drop-out type.

After the selection has been checked, a check relay 3 is pulled and holds over its own front contacts to prepare circuits for subsequent operations on the point selected.

In order to release the set to normal after an operation has beenp'erformed, or for anyv other reason, a release relay H5 is providedin combination with an auxiliary release relay 320. The release relay 3|! is arranged to control -the operation of a release control relay 3 l6, which serves to send theextra long positive release impulse to the sub-station to restorethe set to the normal condition. It will be observed that all of the relays 3|5, 3|6 and 329 are of the extra slow-todeenergize or drop-out type.

An auxiliary sending relay 33| of the slow-todeenergize or drop-out type is provided for initiating the functioning of the positive and negative line relays 30| and 302 a predetermined time after either of the'sending relays 301 or 308 is Pulled.

Common equipment at the sub-station Referring now particularly to Fig. 4 of the drawings, it will be observed that the equipment common to all of the points at the sub-station is there shown- This common equipment is substantially in duplicate of that shown in Fig. 3 of the drawings, and therefore, will not be described in as great detail. I

Positive and negative line relays 40| and 402 are provided having associated therewith the dry .type of rectifiers HR and 42B. These relays are for effecting certain desired control functionswhen a long positive or negativeimpulse is ap plied to the signalling circuit.

Positive and negative impulses are originated at the sub-station by means of positive and negative sending relays 401 and 408, respectively. These relays are of the slow-to-deenergize or drop-out type.

The long impulse from the sub-station is controlled by means of long impulse sending relay 403 whichis of the extra slow-to-deenergize or drop-out type.

After an impulse has been transmitted from the sub-station sending control relays M0 and III are pulled in-order to prevent the sending of a second impulse, and further, to control the circuits for the receipt of the next impulse from the oillce. It will be observed thatthe sending control relay 4| l is provided with a pulling wind-- ing P and a holding winding H, the fielding-winding being provided for maintaining the relay pulled under certain operating conditions when the circuit to thepulling winding is opened.

After a point-has been selected at'the sub-- station, selection cut-01f relay 2 is pulled to prevent the subsequent selection of a. second point until the point selected has been cleared.

When a selection is originated at either station, the receiving circuits are transferred to receivethecheck impulse. This is accomplished by means of a switching relay 4|3 which is of the slow-to-deenergize or drop-out type.

After the check impulse has been received. a check relay 4 is pulled to condition the cir cuits for a subsequent operation.

In order to restore the set to normal, a release relay 5 is provided, together with an auxiliary release relay 4| IA. When the extra long positive release impulse is applied to the signalling circuit, the auxiliary releasing relay IA is Set under normalconditions Assuming that none of the circuit breakers at the sub-station is: closed, the auxiliary switches associated therewith will be in. the open position and the point supervision G relays associated therewith will be dropped. Normally, however,

l the point startI-I relays will be pulled.

It will be observed that certain relays have the reference character X above them. This indicates .that these relays are normally pulled. Thus the H relays associated with points I, 2 and 5 arefurther identified by the reference character X which indicates that normally these relays are pulled, regardless of the position of the circuit breaker associated therewith.

At the ofllce, none of the relays associated with any of the points will normally be pulled. In. the event that any of the circuit breakers associated with points i, 2 and 5 is pulled, then the corresponding point lamp C relay will be pulled. However, since this is not what may be termed a normal condition, these relays are not designated as being normally pulled.

At the office, relays 306, 300, M5, 329 and MI will normally be pulled. The circuits for pulling these relays will be traced hereinafter, and therefore, will not be set forth at this time.

At the sub-station, the following relays, in the common equipment will be pulled: 406, 409, 5, IA and 2A; The circuits for pulling these relays will be set forth in detail hereinafter.

In accordance with customary practice, the negative terminal of the battery at the ofllce or at the sub-station is indicated by means of the negative polarity sign surrounded by a circle. The direct positive terminal of the battery at either station is indicated by means of the positive polarity sign surrounded by two concentric circles. In order to release the set to normal,

it is desirable to drop out simultaneously several 1 of the relays which will have been pulled. This control is effected by connecting these relays to what may be termed positive bus rather than positive battery. Positive bus is indicated by the positive polarity sign surrounded by a, single circle.

At the office, normally dropped release control relay 3l6 serves to connect at its back contacts 3l6b the positive terminal of the battery with the positive bus. When the release control relay M6 is pulled, this connection is opened and all of the relays at the'ofllce which are pulled from the positive bus connection are deenergized.

In like manner, the release relay l5 at the sub-station is arranged to connect at its front terminals 4|5c the positive terminal of the battery to the positive bus. When the release relay M5 is dropped, this circuit is opened and the relays which are pulled at the substation over the positive bus connection are deenergized.

In order to perform certain functions, it f desirable to have the front contacts of certain of the sets of contact members to make before the back contacts are broken. Such a contact arrangement is illustrated as at the contact members 300a; this the back contact is illustrated as being riveted in such. ma'nnet as to permit its following the movable contact member until it first: engages the front contact member. Referring specifically to the release relay 5 it. will be observed that. the make contact member of the set; of contact members 5b isarranged to break after the movable contact member has engaged the fixed contact member.

Explanation of circuit tracing relays, twist keys, point operate keys, and resistors.

No attempt will be made to describe each circuit as traced by words, but rather only the contact members, etc., will be employed through the use of symbols. For example, in order to indicate the third set of contact members of the relay 301, the symbol 301c will be used. In the event that the front contacts of this set of contacts are designated, the symbol will be j301c. If the back contacts of this set of contacts are designated the reference character will be b301c.

No reference character will be applied to the individual resistors which are provided in series with the windings of certain of the relays. These resistors are designated on the drawings by their ohmic values and such will be employed when a resistor forms a part of a circuit.

The winding of any of the relays will be designated by the number of the relay followed by the reference character w. Thus, the winding of relay 301 will be designated as 301w.

Assuming that the positive sending relay 301 has been pulled, the circuit for pulling the positive line relay 0| at the sub-station may be traced as follows:

0| pulls: 200,, bfllc, 1301b, line L2, lfllw, HR, b40811, b401a, line Ll, 1301c,

This circuit in words is as follows: negative battery, resistor 200, the third set of back contacts of relay "I, second set of front contacts of relay 301, line L2, winding of relay I, rectifier MR, first set of back contactsof relay 0, first set of back contacts of relay 401, line LI and third set of front contacts of relay 301 to positive battery.

Outline of detailed description of operation The following, in brief, indicates the opera- V tions which will be described in detail in connection with each of the points. Only a sufficient number of operations will be described in order to indicate to those skilled in the art the functioning of the supervisory control system organized in accordance with my invention. Additional functions or operations will be readily apparent and, therefore, will not be described in greater detail.

Point No. 1

The operation of this point will be described assuming that the circuit breaker associated therewith is in the open position. A selection and check selection operation will be described. After the selection has been checked, the functioning of the system to check the condition of the circuit breaker will then be set forth. After the condition of the circuit breaker has been checked, the circuits will be traced which are used in order to close the circuit breaker. As the result of the closure of the circuit breaker, the corresponding indications will be given at the indicating lights at theomce. The circuits will then be traced showing how the circuit breaker associated with this point is tripped. After the completion of this cycle of operations, the functioning of the system to restore to normal will be set forth.

Point No. 2

The selection and checking of selection of point'No. 2 will be set forth, together with the operations necessary to effect a checking of the position 'of the apparatus unit associated with point No. 2.

Point No. 3

selected a description of the functioning of the tail, together with the remote metering will be set forth indicating how the water level meter at the office is connected first to read the sub-station battery voltage, and then to read the potentiometer voltage which is a function of the water level.

Point No. 4

The selection and check of selection oi point No. 4 will be set forth in detail, together with the means whereby the gate position met'er'is eter voltage which corresponds to the gate posi-' tion. The steps in the operation to open or raise the gate will be detailed, and in like manner, the steps to close or lower the gate will also be set forth. 7

- Point No. 5

In describing the operation of point No. 5 it will be assumed that the circuit breaker associated therewith is in the closed position and that the point lamp relay 205 is pulled to light the red indicating lamp 253. It will be assumed that the circuit breaker associated with this point is automatically tripped. The selection and checking of point No. 5 will be set forth in defunctioning of the alarm light ML and the disagreement lamp flicker relays 232 and 233 in connection with the functioning oi the disagreement lamp Operation of point No. 1

It will be assumed that the operator desires to supervise and operate the circuit breaker associated with point No. I. Therefore, he depresses the point operate key lPOKi to select this point at both the offlce and the sub-station. It will be assumed that the twist key ITKI is in the position illustrated in the drawings, which is the position corresponding to the circuit breaker associated with point No. i in the tripped position. The green light I i4 will be lighted due to the fact that the point lamp relay ICI is dropped. The circuit for energizing the green light 4 is obvi- OHS.

As the result of the operation of the point operate key IPOKI, the start relay 220 is pulled. The circuit for energizing start relay 220 may be traced as follows:

220 pulls: 220w,

1309a, b3llb, bi,

As soon as the start relay 220 pulls it holds over its own front contact members 220a in series with lPOKc, b22011, blllc, b3l4c, D3050, b3|00, fillid, 1130i,

301 pulls: 301w, b3l6c, b30311, IPOKG,

MISC, b3i4c, H0911, IJOBd, bl, b302,

The short positive selection impulse is not applied to the signalling circuit until the auxiliary sending relay 33! drops. The pulling circuit for relay 33l is completed through the back contacts of 301a and the pulling of relay 30'! opens them to drop relay 33L Relay 33| drops due to b301a opening.

As soon as relay 33l relay 30f is pulled. Its traced as follows:

30l pulls: zoo, b33ic, ram, 30iw, am, blCla,

ason, ,f301c,

Therpositive line relay at the sub-station is also energized due to the application of the short positive impulse. Its pulling circuit may be traced as follows:

I pulls: 200, b33l0, f301b, line L2, 40iw,

MR, 174080, b401a, line Ll, H010,

The pulling of relay 30i opens the pulling circuit for the positive sending relay 301. Due to the fact that relay 301 is a slow-to-drop out relay, its front contact members remain closed for the time required for this relay to drop out. It is this time which determines the length of the short positive impulse.

mac, bll lb, b305c, b3l0c.

drops the positive line pulling circuit may be As a result of the pulling of relay 30L relays- 303 and 305 pull in series. The pulling circuit for these relays may be traced as follows:

305 pulls: 305w, f3l5b, 303Pw, ,f30l, b302,

Relay 303 holds over the following circuit:

303 holds: 3031110, 200, 13030, j305a, Q).

In like manner, at the sub-station relays 403 and 405 pull in series; Their pulling circuit may be traced as follows:

403, 405 pull:

Relay 403 holds over the following circuit: 403 holds: 403Hw, 200, #031), fll5b, H050, 69.

Nola, b30811,

405w, fflia, 4031310, "0|,

Relay 3I0 holds over the following circuit:

are pulled, the holding circuit for relay 3|0 will be opened and it will subsequently drop.

As set forth hereinbefore, the pulling circuit for the sending relay 301 was opened due to the pulling of the positive line relay 30L It now drops and as a result, the auxiliary sending relay 331 is pulled. Its pulling circuit may be traced as follows:

33l pulls: 33MB, D3010, D3080,

As soon as the positive sending relay 301 drops, the pulling circuit for the positive line relays 301 and 40l is opened and as a result, they drop. The dropping of the line relays 301 and 40l opens the pulling circuit for relays 303 and 305 at the office, and relays 403 and 405 at the sub-station. However, due to the fact that the neutral receiving relays 305 and 405 are of the slow-to-drop out type, the front contact members thereof will remain closed for a certain time and, therefore, the holding windings of the relays 303 and 403 will maintain these relays pulled. It is during this interval that the pulling of the point selection relays individual to point No. I at the office and the sub-station takes place.

The circuit for pulling point selection relay IBI may be traced asfollows:

lBl pulls: lBlw, bllia, f306b, 193040, 130341,

The circuit for pulling point selection relay F! may be traced as follows:

5Fl pulls: SFIw, b4l2a, T4050, b40417, f403a,

305 drops due to 301 dropping. 405 drops due to 401 dropping. 303 drops due to 305 dropping. 403 drops due to 405 dropping.

Sending control relay 3 then pulls in order to set up the circuit for receiving the next impulse from the sub-station. The circuit for energizing relay 3 may be traced as follows:

3 pulls: 3! IP10, b30513, blCSb, J3l0b, blCSc,

Selection cut-off relay 2 also pulls in order to prevent the selection of any other point until point No.1 has been restored to normal. The

circuit for pulling relay H2 may be traced as follows:

H2 pulls: 2w, flBlc, lBlw,

It will be observed that the dropping of relay 303 removed positive battery from IBM and as a result, permitted 2w to pull in series with lBlw.

The circuits are switched to receive the check impulse due to the pulling of the switching relay 3l3. The pulling circuit for relay 3|3 may be traced as follows:

313 pulls: positive battery, b3l4b, 313w, flBIc,

lBlw,

The pulling of switching relay 313 also completed a circuit for energizing the holding winding of the sending control relay 31 I. The pulling At the sub-station, selection cut-off'relay 412 pulls in order to prevent the selection of any other point. Its pulling circuit may be traced as follows:

The dropping of relay 403 opens the pulling circuit for 5F|w by removing positive battery therefrom. Thus 412w is permitted to pull in series with -5Flw.

Check of selection point No. 1

In order to switch the circuits to transmit the checkingpulse back to the ofiice, switching relay 413 is pulled. Its pulling circuit may be traced as follows:

3 pulls: 69, 124140, 4l3w, j5Flc, 5Flw,

At the ofiiceswitching relay 3l3 pulls over a circuit which may be traced as follows:

3" pulls: 63, 133141), 3l3w, jlBlc, lBlw,

Positive sending relay 401 at the sub-station then pulls to transmit to the oflice a long positive impulse in order to check the selection and to indicate to the operator that the No. 1 point at the sub-station has been selected, which corresponds to the No. 1 point at the oflice. The circuit for energizing relay 401 may be traced as follows:

401 pulls: 401w, jiFla, j4l3b, b4l4b, f409b,

b4llb, b40511, b4l0a, 1405a, b40l, b402,

As a result of the pulling of positive sending relay 401 the pulling circuit for the auxiliary sending relay 412A is opened at back contact members 401a. Due to the dropping of relay 412A a holding circuit is completed for relay 401 which may be traced as follows:

401 pulls: 401w, fSFla, j4l3b, b4l4b, j409b,

b4l2Ac. 14010, 114080, 69.

As a result of the pulling of the positive sending relay 401 and thedropping of the auxiliary sending relay 4I2A, the positive line relays 30l and 401 at the oflice and sub-station, respectively, pull as follows:

401 pulls: 200, b4i2Aa, 1401b, 40lw, MR, 3500,

30! pulls: 200, b4l2Aa, f401b, line L2, 30lw, 3IR, blC3a, 0308c, b301c, line LI, 1 401a,

It will be observed that the line relays at the station originating a sending impulse pull through a 3500 ohm resistor. Thus, when the positive sending relay 301 is pulled the positive line relay 30! pulls through a 3500 ohm resistor, while the positive line relay 40! pulls directly through the line. In like manner. when the positive sending 15 pulls through a 3500 ohm resistor, while the posirelay 401 is pulled the positive line relay 40I tive line relay 30| pulls through the line. The 3500 ohm resistor is arbitrarily chosen as representing a line having that amount; of resistance.

In order to balance the pulling circuits for the line relays, it is desirable to use-the line balpuns. i 05b lob M050 a ancing resistor in the manner indicated. If the signalling circuit or line has a smaller resistance,

of course the value of this resistor will be correspondingly reduced.

At the sub-station, relays 403 and 405 pull in series and at the oflice, relays 303 and 305 pull in series. Since the circuits for these relays have previously been traced, they will not again be' repeated. Relays 403 and 303 hold'over circuits which have been previously traced.

It willbe' observed that the holding circuit for relay 401 does not include the back contact members of relay 40| and, therefore, the winding of relay 401 is not deenergized as soon as the positive line relay MI is pulled.

The positive sending relay 401 holds over con- I tact members of the long impulse sendingrelay 409 and his not until this relay dropsthat the winding of relay 401 is deenergized.

At the sub-station relay 410 pulls to prevent any further sending of impulses from the substation. The circuit forrpulling relay 0 may be traced as follows: i

relay 0 will be opened and this relay will drop.

At the ofilce, relay 3|0 drops due to the fact that relay 3 had previously pulled and that relay 305 is now pulled.

Due to the fact that the positive line relays 4M and 30! are pulled for an extra long time, long impulse receiving relays 405 and 306- drop out, that is, the pulling circuits for relays 406 and 306 are open for a sufliciently long time to permit these extra slow-to-drop-out relays to drop out.

Due to relay -4l2A being dropped for an ext a long time, the holding circuit for relay 40 is opened and this relay drops. Asa result of the dropping of relay 409, the previously traced holding. circuit for the positive sending relay 401 is opened and it drops. The dropping of positive sending relay 401 completes a circuit for pulling relay 4 I 2A which may be traced as follows:

2A pulls: 4l2Aw, 174010, 174000, 69.

Relays 405 and 305 drop due to relays 40L and 30! having previously dropped. As a result, the

new, M061); M040,

I impulse from the office. The circuit for H3 and 3l3 are opened.

holding circuits for relays 403 and 303 are opened and these relays drop.

At the sub-station, relay 4 pulls to prepare the circuits for the subsequent reception of an pullin relay 4 may be traced asfollows:

Due to the pulling of check relays 4M and 3, the pulling circuits for the switching relays The switching relays now drop out. v A

As aresult of the dropping of the receiving relays -403 and 303, relays 406 and 409 are pulled at the sub-station, and relay 306 is pulled at the oflice. The circuits for pulling these relays may be traced as follows:

300 pulls: 306w, 123040, b303d, b30l, b302,

300 holds: 30610,)30611, b30l, b302,

Due to the dropping of relay 3I3 the holding circuit for 3| lHw is opened and relay 3 drops. j The stop lamp 0 associated with point-No. 1

1 nowis lighted to indicate to the operator that the point which he has-intended to select has, in

- fact; been selected. The circuit for lighting stop lamp H0 may be traced as follows:

Stop lamp lights: ll0, flBla,-b3l3b, 13m), 9; I

Check of breaker position point No. 1

No further operation will now take place until,

the operator initiates an operation from the oflice. It, will be assumed that he wishes to check the position of the circuit breaker'associated with the No.1 point, and therefore, the check key 20K is operated momentarily. As a result of the operation of the check key ZCK, check control -relay 2i9 pulls. The pulling circuit for this relay may be traced as follows: v

2 l9 pullsi 2l9Lw, 2cm, f220b, f3l4c, f309a,

b3lib, D3050, b3l0c, f306d, b30l, b302, As the result or the pulling of the check control relay 2] 9 the operation control relay M0 is pulled, Its pulling circuit may be traced as follows:

2I8 pulls: 2l0w, ,f2l9b, thence over same circuit It will be observed that relays m and us, hold in over flllb, so that it is not necessary for the operator to hold the checkkey in the ,operatedposition for a longer period of time than is required to pull relay 2l8. g

. In order to check the positional the circuit breaker, a short positive impulse is applied to the signalling circuit by the positive transmitting relay 301. The circuit for pulling relay 301 may be traced asfollows:

{220b,thence over. circuit for pulling relay 2l9..' it r Relay 3" drops due to the pulling of relay 301 and as a result, line'relays 3M and MI at the ofllce and substation, respectively pull over circuits which have previously been traced;

Relays 30,3 and 305 at the 'ofllce pull in series as a result'of line relay 301 pulling. At the substation, relays 403 and 405 pull in series as a result of the positive line relay 30l pulling.

Relay 4 holds over a circuit which may be traced as follows:

At the oifice, sending control relay 3I0 pulls over a circuit which has previously been traced to prevent further sending and this relay holds over a circuit which has aso previously been traced.

At the sub-station sending control relay 4I0 drops due to relay 405 pulling, relay 4 having previously been pulled.

The pulling of relay 30I opens the previously described pulling circuit for relays 2I8 and M9. However, these relays are held over a circuit which may be traced as follows:

As a. result of relay 30I pulling the pulling circuit for the positive sending relay 301 is opened and it drops. Positive line relays 3M and 4M then drop and since the holding circuits for relays 2 I 8 and 2 I 9 are now opened, they also drop.

Relays 305 and 405 drop due to the dropping of positive line relays 30I and 40I, respectively, and as a result, relays 303 and 304 drop.

Relay 3 then pulls to prepare for the release of relay 3"] on the reception of the next impulse over a circuit which has previously been traced.

At the sub-station, as a result of the dropping of the positive line relay 40I, relays 405 and 403 drop.

Since the holding circuit for relay 4 is no longer completed at contacts f405b, it drops.

Since the circuit breaker associated with point No. 1 is tripped, a short negative impulse is applied tothe Signalling circuit by means of the negative sending relay 408, which is now pulled. The pulling circuit for relay 408 may be traced as follows:

408 pulls: 408w, b404 0, biGIa, ISFId, j4l4b, f403b, b4llb, b40511, b4l0a, f406a, b40l, b402,

Relay 4I2A drops due to the pulling of the negative sending relay 408 and then negative line relays 402 and 302 pull, in response to the application of the negative impulse to the signalling circuit over circuits which may be traced as follows:

At the sub-station relays 404 and 405 pull in series. This circuit may be traced as follows:

404, 405 pull: 405w, {415a, 404Pw, 1402, 404 holds: -,404Hw, 200, 14040, j4l5b, 14050, 6).

At the ofllce, relays 304 and 305 pull in series over a circuit which may be traced as follows:

304, 305 pull: 305w, ,f3l5b, 304Pw, i302, 304 holds: 304K11 200, j304b, 1305a, 6).

Relay 3 holds over a circuit which may be traced as follows:

3 holds: 3IIPw, 1305b, jlIla,

At the sub-station, sendingcontrol relay 0 pulls to prevent further sending over a circuit which may be traced as follows:

b405c, 69. 4) holds: 4I0w, f4l0b, b4IIc, G9.

At the oflice relay 3I0 drops due to the neutral receiving relay 305 being pulled and relay 3 having previously been pulled.

Since the negative sending relay 408 is pulled through the back contacts of negative line relay 402, it drops due to these back contacts being opened. Therefore, it will be understood that the lengths of the short negative impulses are controlled by the drop-out time of the negative sending relay 408. At ,the office negative line relay 302 also drops due to the dropping of the negative sending relay 408 at the substation.

In view of the .iact that the green indicating light H4 is lighted due to the point lamp relay ICI being dropped, no further operation takes place at this time. However, had the point lamp relay ICI been pulled and red indicating lamp II3 lighted, it would be apparent that the position of the circuit breaker did not correspond to the indication given at the office. Therefore, the winding of the point lamp relay ICI would have been shunted down at this time over a circuit which may be traced as follows:

Shunt circuit for ICIw: b302, b30I, b30311, 1304a, ,f306a, -b3Il, b3l0a, j3l4a, b3I3a, fIBIc,

ICIw.

Since positive battery would be applied to both terminals of 'ICIw "under these conditions, it would be shunted down if it had been pulled.

After the position of the circuit breaker at point No. 1 has been checked, relays 305 and 405 drop and as a result, relays 304 and 404 drop.

Relay 4| I ,drops-due to the dropping of the relay 305 which opens the previously traced holding circuit for relay 3| I.

At the sub-station, relay 4 pulls over a circuit which has previously been traced to prepare for the reception of an operation impulse transmitter from the :ofiice.

Closing the circuit breaker point No. 1

232 pulls: -,'232w, m, ITKIa,bICIa, m pulls: 233w, m2,

The pulling of relay 233 places negative battery on both sides of 232w, causing it to be shunted down and to permit full voltage to be applied to the disagreement lamp III. The shunting down of relay 232, however, opens the pulling circuit for relay 233 and it then drops. Removal of the negative battery from both sides of 232w permits relay 232 to pull in series with the disagreement lamp III and it is extinguished. This cycle of operation continues until ,the point lamp relay ICI is pulled to cause the indicating lamps at point No. 1 to-correspond to the position of the twist key ITKI, or until he returns twist key to original position.

- over the signailingcircuit by the successive pulling and dropping out of the transmitting relays 301 and 300. In order to initiate the control impulse the master control key 2MCK is depressed which, in turn, causes the operation control relay 2" to pull over a circuit which may be traced as follows:

H8 pulls: 2l8w, IMCKa 1220b, fll4c, {309a, bll lb, M050, b3l0c, f305d, 1730!, b302,

It will be observed that the operation of control relay 0 holds over its own front contacts 2| 8!),

thereby shunting contact members 2MCKa of the master control key and rendering it unnecessary to hold it in the operated position for a time longer than is necessary to pull relay 2| 0.

Positive transmitting relay 301 is then pulled over a circuit which may be traced as follows:

301 pulls: 301w, b3l6c', b80312, iTKld, ,fIBlb, b2l9a, thence over the circuit for pulling 2i3.

Relay 33| drops due to the pulling of relay 301 arid positive receiving relays 30l and 40i are pulled.

Relays 303 and 305 pull in series over a 'circuit which has previously been traced, and relay 303 holds over a circuit which also has previously being pulled, the holding circuit for relay 0 at the sub-station is opened and it drops.

At the ofiice, relay 300 pulls to transmit the negative impulse as soon as the positive sending relay 30'! has completed sending the positive impulse. The circuit for pulling relay 300 may be traced as follows:

308 pulls: 308w, b30411, fillb, lTKld, flBlb,

b2l0a, flllb, flab, "I46, 1309a, but, f301a, 1730,

It will then be observed that relay 300 will hold in over its own front contacts 300a and that it will not be afiected by the subsequent dropping of positive sending relay 307.

Relay 3M pulls in order to prevent-further sending after the control impulse has been transmitted. Its, pulling circuit may be traced as follows:

m pulls: mt, b3i0b, mac, b3llb, bum,

m holds: sio, f3l0b, more,

The positive sending relay 301 to the pulling of relay 303 and as a result, the positive line relays 3M and ii drop.

Negative line relays 302 and 402 are immediately pulled due to the fact that relay 301 has dropped and the negative-sending relay 300 has previously been pulled. The circuits for pulling these relays have previously been traced, and will not again be set forth.

Relays 304 and 404 then pull in series with relays 305 and 405, respectively. At this time, it will be understood that both the positive and negative receiving relays 303 and 304 at the office and the corresponding relays 403 and 404 at the sub-station will be pulled.

bao sa, b3i la,

now drops due 'auxiliary sending relay 3 Relay 300 then drops due to the pulling of relay 304, and, in turn, the operation control relay 2" drops .due to the dropping of relay 300. The then pulls since now both the positive and the negative sending relays 301 and 308 have dropped. Negative line relays 302 and 402 drop due to 300 dropping.

Due to the circuits which have been completed by relays 403 and 404 being pulled at the same time, the closing relay SCI is pulledover a circuit which may be traced as follows:

Due tothe pulling of closing relay 5Cl the circuitbreaker associated with this point is'operated to the closed position, as will be readily understood.

Neutral receiving relays 305 and 405 drop due to the dropping of negative line relays 302 and 402 respectively. As a result of the dropping of relays 305 and 405, relays 303 and 304 at the oflice and relays'403 and 404 at the sub-station drop.

Relay 4 drops due to the dropping of relay 405 which opens the holding circuit that had previously been set up for this relay. At the office, relay 3 is pulled as soon as relay 305 drops over a circuit which has previously been traced.

Due to the closing of the circuit breaker associated with point No. 1, auxiliary switch SASI closes to complete an obvious circuit for pulling point supervision relay IGI- Due to the opening of the back contacts of 5Glc, the closing relay 5Cl drops. Also due to the opening of the back contacts 5Glb, the point start relay 5Hl drops. It will be observed that the point start relay 5H! was held in over its own front contacts IBM. The movement of the contact members 5Gib is sufliciently slow to permit the winding of the point start relay 5Hl to be deenergized, while the movable contact member is moving from. the back to the front contact member.

Supervision of point No. 1

When the circuit breaker associated with point No. I has been operated to the closed position, it isdesirable that an indication of such operation be given to the oflice, which indication will be in the form of the lighting of, the red indicating lamp 3 and the extinguishment of the green indicating lamp 4. A supervision impulse comprising a short positive impulse is transmitted from thesub-station to the mice by the positive sending relay 401. The circuit for energizing relay 401 may be traced as follows:

401 pulls: 401w, time, new, llFld, )4l4b, nose, b4llb, mm, b4l0a, f400w, b40l, b402,

Auxiliary sending relay 4I2A then drops due to the pulling of relay 401 and as a further result positive line relays 4M and "I are pulled over circuits which have previously been traced.

At the offlce positive and neutral receiving relays corresponding relays 403 and 405 pull. At the 303 and 305 pull and at the sub-station the sub-station relay 4'l0 pulls over a circuit which and imme- 7 and, in turn, to pull the positive sending relay diately the positive line relays I and "I drop. Also due to the dropping of positive sending relay "1 the auxiliary sending relay 2A is again pulled.

Supervision relay I" at the oiilce now pulls in order to pull the point lamp relay iCi for the purpose of lighting the red indicating lamp lli'and extinguishing the green indicating lamp "4., The circuit for pulling relay ll! may be traced as follows:

ll! pulls: il'lw, fllib, Mlle, mac, bill,

bill,

lnresponsetothepullingofthesupervisicn relay 3" the point lamp relay i0! is pulled over a circuit which may be traced as follows:

ICI pulls: Ill, fill, blllc, fills, bllta,

flBle', lClw,

ICI holds: lchv, jiclb, llll,

lhe neutral receiving relays 3.5 and ll! drop ,due to the dropping of the corresponding positive line relays 3|! and ill and as a result, relays I" and I" drop. 'lhe holding circuit for relay 3 at the oflioe having been opened due to the dropping of relay SIS, it drops, while at the substation, relay Ill pulls over a circuit which has previously been traced. As a further result of relay SIS dropping, the pulling circuit for the supervision relay Si! is opened and it drops.

The circuit breaker is now in the closed position and at the oilice, the twist key corresponds to this position and the red indicating lamp is lighted. No further operation will take place at this time until an operation is initiated by the operator.

Trip circuit breaker point No. 1

While still on point No. i it will be assumed that the operator wishes to trip the circuit breaker associated therewith. In order to eiiect this operation, he operates the twist key iTKi to the trip position, which is the position in which it is illustrated in the drawings. The disagreement lamp flicker relays 232 and 213 are again caused to operate to flash the disagreement lamp Ill. The circuit for pulling relay 2!! may be traced as follows:

232 pulls: 132w, iii, I'I'Klh, iiCla,

The subsequent operation of the flicker relays 232 and 233 will be as described hereinbeiore and will not be repeated.

The operator then depresses the master control key to pull the operation control relay 2l8 301 in order to send a long positive impulse for effecting the trip operation. The circuits for energizing these relays may be traced as follows: 2l8 pulls: 2|8w,2MCKa, 1228b, fillc, mac,

btl lb, bilic, billc, fillid, b301, b3|l2, 301 pulls: 301w, biltc, i'I'Kic, jiBib, bliSa, 1228b, nub, thence over the circuit for in. Due to the pulling of relay 301, the auxiliary sending relay 33! drops. Relay 391 then holds over a circuit which may be traced as follows: 30! holds: 301w, b3i6c, lTKic, flBlb, Misc, filth, full), flue, 1369a, b33111, fllla, bSNa, Positive line relays an and "i will be pulled due to the application of the positive impulse to the signalling circuit. Since the winding of re lay 30'! remains energized over the holding circuit it will not drop out due to the pulling of the positive line relay 301.

At the oflice, relays 303 and 385 pull in series areas-1o and at the sub-station the corresponding relays ll! and 5 pull in series. At the ofllce, relay Ill pulls and at the sub-station relay ll! drops.

Due to the fact that positive line relays ill and I are pulled for an extra long time, the 5 long impulse receiving relays I and 4" drop. Due to the fact that the auxiliary sending relay "I attheoiilceisdroppedioranextralong time, the long impulse sending relay III is dropped. The dropping oi the long impulse saiding relay Ill opens the holding circuit for the positive sending relay 3" and it drops. pulling the auxiliary sending relay 33L 'ihe positive line relays "I and "I then drop due to the dropping of the positive sending relay 3|]. As a further result of the dropping of relay "I the operation control relay 2|! which had previously been held over the front contacts of "la, drops.

At the sub-station the trip relay S'Il pulls over a circuit which may be traced as follows:

STI pulls: illHw, bllta, flila, bliic, Mic,

jiGlc, i'rlw, blltc, blllb, fllja, blli, our.

STI holds: ll lHw, blliu, .illlc, bl'ilc, iil 'le,

fSGlc, S'Ilw, iSTia, bill, b102,

The circuit breaker then trips in response to the operation of the trip relay Tl.

At the oiiice, as a result of the dropping of the positive line relay "I relay SIS is pulled and it holds over circuits which have previously been traced. Likewise, relay it! pulls and holds over circuits which may be traced as follows:

3l! pulls: "9w, btlsb, Hide, 4-.

it! holds: "5w, filth, I33"),

Neutral receiving relays 305 and I" at the oiiice and sub-station drop, and as a result, positive receiving relays 3'3 and I drop.

Due to the tripping of the circuit breaker, auxiliary switch SASI is opened and the point supervision relay 5G! drops. Also at the substation relay lil drops and due to the fact that relay GI has dropped, the tripping relay 5T1 drops It is then desirable to transmit a supervision impulse hack to the oiiioe to indicate that the circuit breaker associated with point No. l is in the tripped position. This is accomplished by transmitting to the oiiice a short negative impulse, by the pulling of the negative sending relay ill over a circuit which may be traced as follows:

Ill pulls: 408w, bllla, bSGia, ,fSFid, flilb, flab, bll lb, bltia, blila, fllia, bill, b102,

Relay "2A drops due to relay "8 pulling.

Negative line relays SI! and III! pull over circnits which have previously been traced in response to the pulling of the negative sending relay 8. The negative and neutral receiving relays land "5 at the oilice and I and "5 at the sub-station are pulled in series as has been set forth hereinbeiore. while at the oiiice. the sending control relay 3!!! drops due to the pulling of relay 385 and at the substation relay I]! pulls and holds over circuits which have previously been traced.

Due to the pulling of negative line relay 2 the pulling circuit for the negative sending relay in I" is opened and it drops. Relay "2A pulls and negative line relays "I and 2 drop.

As a result of the pulling of the negative receiving relay 3", positive battery is applied to both sides of the winding of the point lamp 7:; 

